Highly Sensitive Detection of Ionizing Radiations by a Photoluminescent Uranyl Organic Framework

Abstract

Precise detection of low-dose X- and γ-radiations remains a challenge and is particularly important for studying biological effects under low-dose ionizing radiation, safety control in medical radiation treatment, survey of environmental radiation background, and monitoring cosmic radiations. We report here a photoluminescent uranium organic framework, whose photoluminescence intensity can be accurately correlated with the exposure dose of X- or γ-radiations. This allows for precise and instant detection of ionizing radiations down to the level of 10 Gy, representing a significant improvement on the detection limit of approximately two orders of magnitude, compared to other chemical dosimeters reported up to now. The electron paramagnetic resonance analysis suggests that with the exposure to radiations, the carbonyl double bonds break affording oxo-radicals that can be stabilized within the conjugated uranium oxalate-carboxylate sheet. This gives rise to a substantially enhanced equatorial bonding of the uranyl(VI) ions as elucidated by the single-crystal structure of the γ-ray irradiated material, and subsequently leads to a very effective photoluminescence quenching through phonon-assisted relaxation. The quenched sample can be easily recovered by heating, enabling recycled detection for multiple runs.

The sulfonate group as a ligand: a fine balance between hydrogen bonding and metal ion coordination in uranyl ion complexes

“…72 The solid-state photoluminescence quantum yield (PLQY) for 6 is 0.030 ± 0.001. Such low values have previously been found in other uranyl carboxylate complexes having a pale yellow color; 28 larger values, often associated with green coloring, are still unusual 75,76 (for comparison, the PLQY of uranyl nitrate hexahydrate measured under the same conditions is 24%).…”

1,3‐Adamantanedicarboxylate and 1,3‐Adamantanediacetate as Uranyl Ion Linkers: Effect of Counterions, Solvents and Differences in Flexibility

“…The solid‐state photoluminescence quantum yields (PLQYs) are low (≤ 1 %) for all compounds but 3 , for which the moderate value of 5 % has been measured. Such values are usual for uranyl carboxylate complexes,, [22b], although in some cases much larger yields were found,[30d], comparable to or larger than that of 24 % for uranyl nitrate hexahydrate.…”

Emergence of Uranium as a Distinct Metal Center for Building Intrinsic X‐ray Scintillators

“…Additionally, we measured the quantum yield (QY) of SCU‐9 to be 58 %, which is 1.6 times higher than that of uranyl nitrate hexahydrate (Supporting Information, Figures S6 and S7). This value is also the highest QY among all uranyl hybrid materials reported, presumably originating from the dense structure which significantly restricts non‐radiative relaxation pathways.…”

“…Recently, uranium has been deeply involved in the development of functional materials based on its unique physical and chemical properties, to be used as catalysts for small molecule activation and water reduction, molecular magnets, unconventional superconductors, and luminescent sensors . These are highly beneficial as they support the utilization of depleted uranium in important aspects of a technologically advancing world, instead of being treated as a “waste” awaiting for disposal.…”